if (!($fp = fopen($this->file, "r")))
{
die("Could not read $this->file"),
}

// parse data
while ($xml = fread($fp, 4096))
{
if (!xml_parse($this->xp, $xml, feof($fp)))
{
die("XML parser error: " .
xml_error_string(xml_get_error_code($this->xp))),
}
}

// destroy parser
xml_parser_free($this->xp),
}

// opening tag handler
function elementBegin($parser, $name, $attributes)
{
$this->currentTag = $name,
// set flag if entering <channel> or <item> block
if ($name == "ITEM")
{
$this->flag = 1,
}
else if ($name == "CHANNEL")
{
$this->flag = 2,
}
}

// closing tag handler
function elementEnd($parser, $name)
{
$this->currentTag = "",

// set flag if exiting <channel> or <item> block
if ($name == "ITEM")
{
$this->count++,
$this->flag = 0,
}
else if ($name == "CHANNEL")
{
$this->flag = 0,
}
}

// character data handler
function characterData($parser, $data)
{
$data = trim(htmlspecialchars($data)),
if ($this->currentTag == "TITLE" || $this->currentTag ==
"LINK" || $this->currentTag == "DESCRIPTION")
{
// add data to $channels[] or $items[] array
if ($this->flag == 1)
{

$this->items[$this->count][strtolower($this->currentTag)] .= $data,
}
else if ($this->flag == 2)
{

$this->channel[strtolower($this->currentTag)] .= $data,
}
}
}

// return an associative array containing channel information
// (the $channel[] array)
function getChannelInfo()
{
return $this->channel,
}

// return an associative array of arrays containing item
information
// (the $items[] array)
function getItems()
{
return $this->items,
}

}
?>
如果你对ＰＨＰ类较为熟悉的话，那么理解这段代码是相当容易的。如果不太懂的话，那么请直接跳到文章末尾的链接部分，看一篇关于类工作原理的好文章。然后在回来继续阅读上面的代码。
在使用这个类之前，我要特别花几分钟指出其中的一行代码——即上面对xml_set_object()函数调用的那一行。